Lubricant composition containing dispersed calcium acetate



Feb. 18, 1964 LUBRICANT COMPOSITION CONTAINING DISPERSED CALCIUM ACETATE R. H. DAVIS Filed March 30, 1961 I00 l Tapping Efficiency U.S.Addi'rive Concentration so I Calcium Acetate Oleic Acid y j Oleic Acid in Chlorinated Paraffin 40 9) X Tricresylphosphate Percent Additive in lOOs.U.S.Viscosify at IOOF Paraffin Oil INVENTOR. Robert H. DGVIS BY s.

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ATTORNEY United States Patent O 3,121,689 LUBRICANT COMPUSITEON CONTAINWG DESPERSED CALCPUM ACETATE Robert H. Davis, Woodbury, N.J., assignor to oceny Mobil Oil Company, inc, a corporation of New York Filed Mar. 30, 1961, Ser. No. 99,471 5 Claims. (Cl. 252-405) This invention relates to lubricating oil formulations haivng the ability to carry heavy loads and operate under extreme pressure conditions without being corrosive to metals. This invention particularly relates to a lubricant formulation containing calcium acetate in the form of a stable dispersion in lubricating oil.

It is known that calcium acetate imparts load-carrying ability to lubricating oil compositions but unfortunately is not soluble in lubricating oil and hence separation occurs. The lubricant formulation, therefore, soon loses its extreme pressure properties in use as the calcium acet-ate separates in the system. The calcium acetate is abrasive and damages the lubricating system, particularly the circulating pump, to such an extent that the calcium acetate cannot normally be used in lubricant formulations in the form of a slurry.

Various methods have been attempted to maintain calcium acetate dispersed in a lubricating oil but these methods have been found more or less defective. For example, emulsifiers have been tried to provide the lubricant formulation as an oil-water dispersion. In many instances, of course, water is not desired in the lubricant formulation. Furthermore, the emulsion breaks under extreme operating conditions, frequently rendering the composition unable to sustain its load carrying capacity. Other suspending aids have been tried but have been found defective for one reason or another.

It was first established that gross calcium acetate suspensions were as effective on the tapping test as on the 4-ball and other extreme pressure testers. Once this was determined the calcium salts of homologous fatty acids were tested to determine if any were better than acetate. The results are reported on the basis of tapping efficiency. In the measurement of tapping efiiciency of an oil, a series of holes is accurately drilled in a test metal, namely, S.A.E. 1020 hot rolled steel. These holes are subsequently tapped with a series of taps in a drill press equipped with a table, which is free to rotate about the center, being mounted on ball bearings. A torque arm is attached to this floating table and this arm in turn actuates a spring scale so that the actual torque during tapping with the oil being evaluated is measured directly. The same taps used in evaluating the test oil are employed in tapping with a standard reference oil, which has arbitrarily been assigned an efiiciency of 100 percent. The average torque for the test oil is compared to that of the standard and a relative efficiency is calculated on a percentage basis. For example:

Percent Torque with standard reference oil 19.3 Torque with test oil 19.8 Relative eiiiciency of test oil This test is described in Lubrication Engineering, vol. 12, No. 3, May-June 1956, pages 199-203. The base refer- 3,l2l,680 Patented Feb. 18, 1064 ence oil selected was a heavy duty corrosive type having the following characteristics:

The comparative performance data of the various calcium salts tested against the reference oil is shown in Table I hereinbelow as follows:

TABLE I Performance Data-Suspensi0ns of Calcium Salts in 100 Sec. Parafnic Oil Tapping Salt Concentration Eiiiciency,

Weight Percent Ref.

Calcium Formats 20 104 Calcium Acetate Monohydraten 20 104 Calcium Propionato 20 99 Calcium Caprylate 2O 76. 2

It is apparent from the Table I above that calcium acetate and calcium formate were the most effective salts on a percent weight basis. These data correlate with the 4-ball weld tests run on similar samples.

The figure shows a plot of tapping etficiency vs. additive concentration for several additives including a mixture of calcium acetate and oleic acid.

I have discovered that straight-chain carboxylic acids are useful in solubilizing calcium acetate in lubricating oil to form a stable lubricant. Of these acids the C unsaturated acids, such as oleic, linoleic and linolenic acids, are outstanding forming cleanhazy solutions with up to 40 percent calcium acetate, provided a sufiicient amount of the solubilizing acid is used. The other straight-chain carboxylic acids form lubricants suitable as way lubricants, wire drawing lubricants, gear oils or other specialty lubricants wherein relatively high viscosity or excessive body are not detrimental factors. The compositions comprise between .005-40% by weight of the calcium acetate, .005-10.0% by weight of the straightchain carboxylic acid and the balance largely lubricating oils, although very minor amounts of corrosion inhibitors, antioxidants and other specific additives may be present without detracting from the usefulness of the composition. A concentrate may first be formed for dilution with mineral oil. This concentrate may contain .005- 40% by weight of the calcium acetate and .005-% by weight of the straight chain carboxylic acid, the balance being oil.

A list of acids evaluated as dispersants is shown in Table 11 along with stability data. The base formula and method of preparation was as follows.

Obtained from Baker & Adamson Chem, Co. Their data sheet indicates a typical analysis as follows.

Assay Percent Ct1(C; HaO2)2H2O 99.5 Chloride (Cl) 0.01 Sulfate (S04) a- 0.10 Heavy metals (as Pb) 0.001 Iron (Fe) 0.002

Metiod of preparation (180 gm. batch): A concentrate was prepared which contained the acetate, acid and approximately 20 gms. of oil; this concentrate was heated with agitation to 280 F. At this point, the remaining oil, preheated to 250 F. was added and the dispersion was stirred until cool. It should be noted, however, that the method of preparation and ratio of acid to acetate used will vary with type of acetate used; type of finished product desired and available equipment.

For example, if an extremely tacky, polymeric product is desired (as opposed to the free flowing dispersions described in Method of Preparation above) for use as a V1. improver or gear oil additive, I would use a ratio of one part calcium acetate (Baker and Adamson Chemical Company purified grade-heated hours at 425 F.) and two parts oleic acid stabilizer in mineral oil. This mixture would be heated to 270350 F. with agitation.

A polymeric dispersion of hydrated calcium acetate can be prepared by first dissolving the calcium acetate in Water and allowing the water to evaporate. The hydrated calcium acetate is then mixed with oleic acid and mineral oil to produce a concentrate, using only about one-half of the mineral oil of the final product, and the concentrate is allowed to stand for l5 hours. The concentrate is then heated to 200 F. and the balance of the mineral oil is added to produce a final formulation of 10% by weight of the hydrated calcium acetate, 2.5% by weight of oleic acid and 87.5% by weight of mineral oil.

TABLE II Organic Acids Evaluated as Dispersants for Calcium Acetate An attempt was also made to stabilize hydrated calcium acetate (prepared by dissolving B and A acetate in Water and allowing water to evaporate at room temperature) in 100 sec. paratfinic oil by passing the acetate-oil slurry through a homogenizer 6000 psi. (5 passes). Precipitation occurred after V hour at room temperature.

It is noted from Table ll that all the straight-chain carboxylic acids were eiieotive in solubilizing or stabilizing calcium acetate. However, the C unsaturated acids were unusual in providing a fluid product. These formulations provide a suitable lubricant formulation where fluidity is essential. Of course, the other formulations find application as a lubricant where fluidity is not essential such as in lubricating the ways for ship launching, Wire drawing, gear oils, etc.

The amount of oleic acid was varied from 2.5% by weight to l0% by weight while the calcium acetate content was retained at 10% by weight. These tests indicated that the viscosity increased markedly with increasing concentration of oleic acid, the viscosity at 10% oleic acid being double that at a concentration of 2.5 Where viscosity is a factor, therefore, such as in metal cutting oils, the oleic acid to calcium acetate ratio should not be raised above about 1 part oleic acid to 4parts calcium acetate; it was found from these tests that the system becomes less stable when the oleic acid to calcium acetate ratio is lowered below about one part oleic acid a to stabilize 4 parts of calcium acetate. Using this ratio it is possible to prepare dispersions in mineral oil which will remain stable for prolonged periods orf time. This is quite unusual since the amount of dispersant necessary is extremely low on a mole basis, i.e., 0.157 mole oleic/ mole of acetate.

An extensive evaluation was made of various alcohols, amines, other types of acids, and surface active agents to determine the solubilizing eitect of these agents on calcium acetate but they failed to show the tavorable results exhibited by straight-chain, carboxylic acids. With the knowledge, therefore, that straight-chain, carboxylic acids disperse calcium acetate providing a stable composition, a study was made of the effect of variation of the oleic acid-calcium acetate ratio and variations in the percentage of solubilized calcium acetate on performance using the tapping test for comparative purposes. These data are reported in Table III as follows:

TABLE Ill The Efiect of Change in Oleic-Acetate Ratio on Performance Percent Percent Percent Tapping Oleic Calcium 100 Paraf- Efliciency Acid Acetate finic Oil It is seen that tapping e ciency is maximum with the minimum amount of oleic acid, although the fall off in tapping eificiency is small with increase in oleic acid concentration. The percent of each constituent in Table Iii is given on a percent by weight basis.

A series of tests were conducted using salts other than calcium to indicate the dispersing power of straight-chain, organic acids with respect to these salts. The results of these tests are reported in Table IV hereinbelow:

TABLE IV Suspension of Salts by Oleic Acid Using 1:4 Ratio of Oleic Acid to Metallic Acetate Conc. Percent Salt Wt. 100 Stability Paraifuiic Oil Calcium Formats 10 Precipitation. Calcium Oxalate 10 Do. Calcium Propronata 10 Do. Ca cium Caprylata. 10 D0. Barium Acetate. 10 Do. Magnesium Acetate. 10 Do. Sodium Acetate 10 Do.

base oil results in a dispersion that is cloudy, but still effective for many lubricating purposes.

The oleic acid-calcium acetate formulation in paraffin base oil makes an excellent non-corrosive cutting oil which contains none of the conventional extreme pressure additives which are for many reasons undesirable out tolerated only to obtain cutting elficiency. This oil formulation has a tapping eiiiciency of 90% or better, which previously could not be obtained without the use or" compounds such as sulfur, chlorine, etc.

Retaining a ratio of 1 part acid to 4 parts acetate a series of tests was conducted using an increasing amount of calcium acetate by weight. in Table V as follows:

TABLE V Percent Calcium Acetate vs. Performance These data are reported Percent Percent Percent Tapping Calcium Oleie 100 Parat- Efficiency Acetate Acid flnic Oil Percent dispersed additive vs. tapping efliciency has been plotted in the figure. This graph also shows the tapping efficiency for several typical cutting oil additives. It is quite apparent from this data that dispersed calcium acetate is considerably superior to all of these compounds. The calcium acetate was blended with onefourth as much oleic acid and hence the results shown on the figure are on the basis of 1 part oleic acid to 4 parts calcium acetate, the balance being mineral lubricating oil.

The invention has been amply illustrated in the detailed discussion of the invention. These examples are given only to illustrate the invention and are not intended as limitations. The only limitations are found in the attached claims.

I claim:

1. A stable lubricating composition consisting essentially of a major proportion of a mineral lubricating oil, between ODDS-% by weight of calcium acetate and between 0.005-10% by weight of an organic, straightchain carboxylic acid having from 8 to 18 carbon atoms therein, including the carboxyl carbon atom, sur'iicient to disperse the calcium acetate in the lubricating oil.

2. A stable lubricating composition consisting essentially of a major proportion of a mineral lubricating oil, between 0.005-40% by weight of calcium acetate and between 0.005-10% by weight of an unsaturated C organic, straight-chain, carboxylic acid, sumcient to solubilize the calcium acetate in the lubricating oil.

3. A stable lubricating composition consisting essentially of a major proportion of a mineral lubricating oil between 0.00540% by weight of calcium acetate and between ODDS-10% by weight of oleic acid, sufficient to solubilize the calcium acetate in the lubricating oil.

4. Claim 2 further characterized in that the mineral lubricating oil is at least predominantly a paraflin oil.

5. A stable lubricating composition consisting essentially of about 87 /2 by weight of parafiin mineral lubricating oil, about 10% by weight of calcium acetate and about 2.5% by weight of oleic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,163,622 Neely et al. June 27, 1939 2,623,017 Whitney Dec. 23, 1952 2,720,491 Beretvas Oct. 11, 1955 2,940,932 Morway June 14, 1960 

1. A STABLE LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL BETWEEN 0.005-40% BY WEIGHT OF CALCIUM ACETATE AND BETWEEN 0.005-10% BY WEIGHT OF AN ORGANIC, STRAIGHTCHAIN CARBOXYLIC ACID HAVING FROM 8 TO 18 CARBON ATOMS THEREIN, INCLUDING THE CARBOXYL CARBON ATOM, SUFFICIENT TO DISPERSE THE CALCIUM ACETATE IN THE LUBRICATING OIL. 